Fuel control for turbine power plants



Patented Mar. 24, 1953 FUEL CONTROL FOR TURBINE POWER PLANTS Andrew V. D. Willgoos, East Hartford, Conn., as-

signor to United Aircraft Corporation, East Hartford, Conn., a corporation of Delaware Application August 15, 1947, Serial No. 768,815

This invention relates to a control for the fuel supply to the combustion chamber of a compressor-turbine type of power plant.

In power plants operating where the density of the surrounding medium varies, as in aircraft power plants where the density of the air varies with altitude, the pressure of the air at the discharge end of the compressor prior to its entry into the combustion chamber or chambers is also variable. If the fuel nozzle is adapted for the delivery of fuel under such a pressure as to be entrained by the air flowing past it, a change in air pressure will cause a change in the rate of fuel ow unless some compensation for the Variable pressure is made, A feature of this invention is an arrangement for adjusting the fuel pressure as a function of the change in pressure at the discharge end of the compressor or the pressure at the inlet to the combustion chamber.

One feature of the invention is an arrangement for maintaining a fuel pressure at the nozzle which is substantially proportional to the pressure of the air entering the combustion chamber, with the nozzle so arranged as to entrain the fuel in the air as it flows past the nozzle. Another feature is the location of the nozzle at the throat of a venturi through which a part of the air flows, thereby providing a slight pressure drop to assure a flow of fuel from the nozzle.

Other objects and advantages will be apparent from the specification and claims and from the accompanying drawing which illustrates an embodiment of the invention.

Fig. l is an elevation partly in section of a compressor-turbine power plant showing the fuel supply.

Fig. 2 is a fragmentary sectional View through one of the combustion chambers on a somewhat larger scale showing the fuel supply digrammatically.

Fig. 3 is a sectional view similar to Fig. 2 on a larger scale.

The invention is shown in connection with a propeller type of compressor-turbine power plant in which a propeller system l!) and a multistage axial flow compressor I2 are both driven from a turbine I4. The turbine is directly connected to the compressor and through a reduction gear in a housing I 6 to the propeller system. Between the compressor and turbine is an arrangement for adding heat to the gas which, as shown, is a number of circumferentially spaced combustion chambers i8, the inlet 20 of 2 Claims. (Cl. till- 3928) which communicates with the discharge end of the compressor. The outlet 22 of the combustion chamber is connected to the nozzle ring 24 which directs the hot gas against the blades 26 of the turbine.

Each combustion chamber may have therein a centrally located sleeve 28 forming the primary chamber within which the combustion of fuel takes place. The inlet end of the sleeve may have a venturi 30, centrally of which is located the fuel nozzle 32. All of the nozzles are connected as by short pipes 34 to a distributor ring 36 surrounding the power plant.

The nozzles may be of any suitable construction; in the arrangement shown in Fig. 3, the nozzle 32 is of familiar carburetor construction and consists of a hollow tube 38 mounted in a supporting bracket 40 and having a number of radial passages 42 communicating with a fuel passage 44 in the bracket. Cooperating with the nozzle and in line with the tube 38 is an inlet pipe 46 having its inlet end smaller than the remainder to convert the Velocity energy of the air entering the tube into pressure energy there- Y in. The discharge end of the tube carries a head 43 having a number of radial passages 50 communicating with the hollow interior of the tube for the discharge of fuel into the air stream passing through the venturi 30. It will be noted that the head 48 is located approximately at the venturi throat, although adjustment of the fuel-air ratio may be obtained by longitudinally shifting the nozzle in the venturi.

Fuel is supplied from a tank 52 through a pipe 54 to a pump 55, the discharge pressure of which is maintained substantially constant by a pressure relief valve 53. A throttle Valve on the discharge side or" the pump controls the supply of fuel to the pressure control valve 62 from which fuel reaches the distributor pipe through a conduit 64.

The pressure control valve 62 may comprise a plunger Gt within a cylinder 68 with one end of the cylinder connected as by a conduit 10 to the inlet of the combustion chamber so that the pressure acting on the end of the plunger 65 is the same as that at the inlet of the combustion chamber. The conduit 64 extends from the opposite end of the cylinder 68 to the distributor pipe 36. The fuel inlet pipe enters a port 'l2 in the cylinder spaced from the end of the cylinder and substantially in line with a port 14 in a cylindrical portion 16 of the plunger. By this arrangement the pressures in opposite ends of the cylinder are maintained equal. If the again balanced.

pressure at the inlet to the combustion chamber decreases, plunger 66 shifts to the left to place part 'I4 further out of alignment with port 12 to decrease the flow of fuel to the nozzle. Equilibrium is established when the pressures are If the pressure at the inlet increases, plunger 66 vshifts to the right to bring; port 14 more nearly in alignment with portv12 to increase the flow of fuel until the pressures are balanced. A fuel return pipe '18 permits the return of any leakage fuel to the tank 52,. By..

the arrangementl shown, fuel is made' available...

at the inlet to the nozzles 32, to be drawn into the burners in proportion to the owY of" arf. through the venturis in which the nozzles-are located.

In operation, air enteringr the cornlsmstiorichamber passes around the cylinder 28 and also through the venturi 30 and into the cylinder:

As it passes through theventuri, it entrains fuel escapinggthrough the, passages 50 and; combus tionof the. fuel:` and; airfin the cylinder; 2.8:V occursi of the cylinder. rnixeswithA the f uel entering-the tube 38 through the` passages *d2-land' assists, in the atomizaticn` of thefuel asitzentzersgthegair streamin t-heyen-` turi.; Asthefair pressure atthe inlet: 2l)v totheV c ombustionchamber increases, the plungervBS'. is: moved'` t0 thelrighnthereby increasing theowf areav through the porti 'Ii'and increasing the pressure in the righthand: endv of :the cylinder- 68; andft-herefore; increasing the fuelpressure at the-nozzle;

It,I to.v ybe understood thatY the invention is.y

notglirn-ited; :to thefspecificA embodimentVV herein; illustrate kanddescribed', but may be 'usedl in other waysgwithoutf departure; from its` spirit.

asdened byfthe,followingy claims.

I' claim:

l. In an aircraft', gas turbine power. pla-nthay. ing a corfllliessor,y afburner, means for-.supplyi-1 ing-fuel tosaidfburner; and; anozzle- Within said burner through which-incluis admittedv to said ff burner, thatimprcvementfor. metering fuel:

sor,discharge.,pressureand the other'end of; the

plunger being subjectto' nozzle'pressure, means-- for admitting fuel totheinterior of saidl cylinf Additional: air enter the cylinder *.28; through; passages; 8,05 adjacent to the, inletfi end Air entering the sleeve, Malso.

der, a port in the plunger Wall, and a passage in the plunger whereby said port is Vented to the nozzle pressure end of the plunger, the port shifting with respect to the fuel admitting means to meter fuel as a function of the pressure diiferential across the plunger and tending to maint'ainrnozzle pressure substantially proportional to compressor discharge pressure.

2. In an aircraft gas turbine power plant having a compressor, a burner, means for supplying fuel to saidv burner, and a nozzle Within said burner through which said fuel is admitted to said burner, that improvement which comprises a Venturi mounted; Within the inlet of said burnersai,d` nozzle 'being mounted Within the throat of said Venturi, a cylinder one end of which is connected to ,compressor discharge pressure and the other end of which is connected to nozzle pressure, a iioating plunger within the cylinder, one end of the plunger being subject to compressor' dischargepressure and the other end of the'plunger beingsubje'ct* t'o nozzle pressure; means for admittingruel to .the interior-Lof said cylinder, a port in the-plungerwall; and a passage in fthe plunger whereby saicif-1ecrtA is ventedto the nozzle pressure'end of the plunger,` the porty shifting with respect to the; fuel'admitting means tometer fuelY asv a function of the pres-V sure differential across theplunger and tend-A ing to maintain nozzle vpressure substantially proportional -to compressorA discharge pressurel ANDREW', V.Y D. WILLGOOS.

REFERENCES 01mm The following,referencesv are ofjrecord' in the file lof this patent;Y

UNITED STATES: l PATENTS 1 

